Chemicals that can cause cancer and other adverse health effects such as harm to the human respiratory system are known as toxic substances. When these toxic substances are released in the air in the form of fine particles or gasses, they are called air toxics. Air toxics that exist as particles can include heavy metals, such as cadmium, mercury, chromium, and lead compounds, as well as organic compounds, such as diesel particulate matter (DPM) and polycyclic aromatic hydrocarbons (PAHs), which are emitted during the combustion of fossil fuels. Gaseous air toxic pollutants include benzene, toluene, and xylenes, found in gasoline; formaldehyde from the combustion of fossil fuels; and ethyl benzene used as a solvent by various industries. Whether air toxics have a harmful effect on an individual’s health depends upon a number of factors, including the concentration of toxics in the air, the length of exposure, and the age and general health of the persons exposed.
The State of California Air Resources Board (CARB) and the United States Environmental Protection Agency (EPA) have created lists of air toxics for various regulatory purposes.
The California Health and Safety Code section 44321 requires CARB to "compile and maintain a list of substances" that must be quantified and reported under the AB 2588 Air Toxics "Hot Spots" program. The list of substances can be referenced in Appendix A of the Emissions Inventory Criteria Guidelines Report (EICGR) which can be found on CARB’s "Hot Spots" Inventory Guidelines website↗.
According to Section 39655 of the California Health and Safety Code, a toxic air contaminant (TAC) is "an air pollutant which may cause or contribute to an increase in mortality or an increase in serious illness, or which may pose a present or potential hazard to human health." OEHHA is responsible for assessing the cancer and non-cancer health related impacts from air borne pollutants and identifying whether those pollutants are TAC. Substances identified as TACs are potentially subject to control measures created by the state. More information on state TACs can be found on the CARB Identified Toxic Air Contaminants website↗.
Hazardous Air Pollutants (HAPs) are air toxics that are known or suspected to cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental effects. EPA works with state, local, and tribal governments to reduce air emissions of 189 HAPs to the environment.
Substances which have been listed as federal HAPs pursuant to section 7412 of Title 42 of the United States Code are TACs under the state's air toxics program pursuant to section 39657 (b) of the California Health and Safety Code. Substances identified as HAPs are potentially subject to control measures created by the EPA. More information on federal HAPs can be found on EPA’s website↗.
